An extreme example of separating what may have been a single Expres app into multiple applications with a host to bring them back together.
Express is one of the most flexible web hosting libraries I have used in my career. I love how simple it can be, and how it allows you to grow your system as needed.
One of the areas that has continued to bother me in my own code, is my lack of ability to cleanly separate different parts of my express app while having those parts hosted in the same root domain name.
Previously, I had separated what may have been a /admin
route into a
completely separate sub-domain, like http://admin.example.com
.
With the realization that Express application instances can be mounted into other Express application instances, however, that changed.
While I do see value in moving /admin
out to a separate sub-domain, still,
I also see a lot of value in separating /admin
into it's own project folder
and still mounting it as /admin
in the main Express app.
This repository is a demonstration Express' ability to do just that - to take what would have been cluttered code from multiple route paths, separate them into their own application instance, and bring them back together in a single application host.
I call this an "extreme example" because I have purposely taken the separation out to the edge of what I might consider useful. Taking this to an extreme allows us to see the bounds of where this might be useful.
It is still possible to take this separation of apps further, creating more sub-applications to split further responsibilities apart.
For example, you could split the "development" vs "production" error handlers into separate app instances, and only mount the one you need.
However, this might really jump the bounds of usefulness... depending on your circumstances, of course. :)
Clone the repository, then
npm install
from the root foldernpm start
from the root folder
node host/bin/www
This demo project is split up into multiple Express application instances, each of which handles a specific portion of the over-all web application.
The primary application is:
host
: The root express app and the actual web server into which the other apps are mountedThe sub-application instances include:
api
: Mounted at /api
, handles the JSON based API access for the appweb
: Mounted at /
, handles the core web pages for browser based usageerrors
: Mounted in the root express app, handles root level 404 and route / middleware errorsYou'll note in each of these projects, that various parts of the default Express app (as generated by the Express-Generator project) have been removed.
For example, the api
project does not need to render any Jade views, so the
view engine registration and views folders have been removed from this project.
Similarly, none of the sub-applications need to have actual web server code
from the bin/www file - only the host
application needs this.
By separating the application into multiple sub-apps, code is easier to maintain as it contains less clutter from unrelated things.
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Distributed under MIT License.